It is presently known in the internal combustion engine industry, and particularly in the medium and heavy duty truck industry, to select engine fueling strategies based on presumed geographic conditions, wherein the geographic conditions are presumed from certain engine and/or vehicle operational parameters. In one known system, engine acceleration is monitored, presumed geographic conditions are determined therefrom and an appropriate one of a pair of fueling strategies is selected based upon the presumed geographic conditions. For example, during periods of continuous accelerations (i.e. stop and go traffic), the vehicle is presumed to be operating in or near a city, and a low emissions engine fueling map is selected for operation in accordance therewith. Conversely, during periods of steady state engine operation, the vehicle is presumed to be operating on an open highway, and a fuel economic engine fueling map is selected for operation in accordance therewith.
While engine fueling control systems of the foregoing type have been somewhat helpful in reducing emissions in areas designated by the Environmental Protection Agency (EPA) as non-attainment areas, they have several drawbacks associated therewith. For example, due to the engine acceleration-based determination of presumed geographic conditions, the foregoing system will typically select the fuel economic engine fueling map when driving on city freeways and beltways, thereby increasing vehicle emissions in or near low emissions urban areas.
As another example drawback, engine fueling control systems of the foregoing type typically switch to the fuel economic engine fueling map only after prolonged periods of steady state engine operation. Thus, during stops in rural areas, such as at weigh stations and toll booths, such systems typically revert back to the low emissions fueling map. The same result occurs when the vehicle is in operation and the vehicle operator is required to interrupt steady state engine operation, such as when downshifting to negotiate a steep grade or when slowing down the vehicle in construction areas. In either case, fuel economy unnecessarily deteriorates.
As yet another drawback, known engine fueling control systems of the foregoing type provide for selection between only a fuel economic or a low emissions engine fueling map. However, either engine fueling map may be undesirable, or even counterproductive, under certain conditions requiring increased engine output (either via engine output power or engine output torque), such as when climbing steep grades. Increased engine output under such conditions would be advantageous in several respects. For example, vehicle operators would be grateful for increased engine output when driving through mountainous regions, and such increased output would reduce the need to down-shift, thereby reducing wear and tear on vehicle components. Moreover, such increased output would likely decrease transit time and allow vehicle operators to pass similarly rated vehicles while still maintaining good fuel economy. Further, vehicle purchasers could purchase lower rated engines and still get higher engine output when needed. The lower rated engines would resultantly last longer than the higher rated predecessor engines, and customer satisfaction would likely correspondingly increase.
What is therefore needed is a system for controlling engine fueling which overcomes the drawbacks of known engine fueling control systems. Ideally, such a system should control engine fueling based on actual (or somewhat accurately estimated) vehicle location/position. Such a system could dramatically reduce emissions in low emissions areas and more accurately enable an appropriate engine fueling map regardless of the states, trends or statuses of engine/vehicle operational parameters. Such a system should further make available not only fuel economic and low emissions engine fueling maps, but should further provide for one or more higher output engine fueling maps to assist vehicle operators in hilly or mountainous regions.